The invention relates to an apparatus and method for controlling the level of a liquid in a tank.
There are various types of devices in use for controlling the level of a liquid in a holding tank. These devices often include a float of some type which rides on the surface of the liquid. The float usually activates a pressure transducer or some other device designed to open and close an inlet valve in response to the level of liquid in the tank.
The liquid level sensors described above have several drawbacks. First of all, these devices must come in contact with the liquid to perform their sensing function. This can cause the sensors to stick or become plugged off as a result of corrosion or solid particles in the liquid. The resulting malfunction of the floats or pressure sensors may allow the inlet valve to remain open and cause an undesirable overfill condition. Floats and pressure sensors are also unreliable devices for determining the level of liquid in a tank when the liquid is under agitation.
For the reasons described above, most of the liquid level sensing systems in use today have the potential for initiating a hazardous situation, such as fire or explosion. The present invention completely eliminates the need for any kind of sensors which must come in contact with the stored liquid, so that it provides a "fail safe" system for controlling the level of the liquid in a tank or other vessel.